Problem: Tiffany ate 4 slices of cake. Luis ate 1 slice. If there were 4 slices remaining, what fraction of the cake was eaten?
Answer: $\text{fraction of cake eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ Since they ate 5 slices of cake with 4 slices remaining, they must have begun with 9 slices. They ate ${5}$ out of $9$ slices. They ate $\dfrac{5}{9}$ of the cake.